* nscp/nscp.c: Makes some attempt to recognize and handle telnet

        IAC codes.  This allows CTRL-C and CTRL-D to work from the client
        for people who get stuck and don't want to use CTRL-].  It's a
        very dirt-simple implementation of the telnet protocol so only
        standard Unix telnet is supported.  The win32 telnet client sends
        too many IAC's that I do not care to handle at this time, so they
        are just dropped with a warning sent to the server.log.
        (GetLine): password is no longer echoed back to the client.

ChangeLog

@@ -1,3 +1,14 @@
+2000-08-21 Kriston J. Rehberg <[email protected]>
+
+ * nscp/nscp.c: Makes some attempt to recognize and handle telnet
+ IAC codes. This allows CTRL-C and CTRL-D to work from the client
+ for people who get stuck and don't want to use CTRL-]. It's a
+ very dirt-simple implementation of the telnet protocol so only
+ standard Unix telnet is supported. The win32 telnet client sends
+ too many IAC's that I do not care to handle at this time, so they
+ are just dropped with a warning sent to the server.log.
+ (GetLine): password is no longer echoed back to the client.
+
 2000-08-20 Kriston J. Rehberg <[email protected]>
 
  * nsftp, nspostgres, nssolid, nssybpd moved to $TOP level.

nscp/nscp.c

@@ -35,7 +35,7 @@
  * Tcl commands.
  */
 
-static const char *RCSID = "@(#) $Header: /Users/dossy/Desktop/cvs/aolserver/nscp/nscp.c,v 1.4 2000/08/15 20:24:33 kriston Exp $, compiled: " __DATE__ " " __TIME__;
+static const char *RCSID = "@(#) $Header: /Users/dossy/Desktop/cvs/aolserver/nscp/nscp.c,v 1.5 2000/08/21 17:53:02 kriston Exp $, compiled: " __DATE__ " " __TIME__;
 
 #include "ns.h"
 
@@ -54,7 +54,7 @@ static Ns_ThreadProc EvalThread;
 static Ns_SockProc AcceptProc;
 static Tcl_CmdProc ExitCmd;
 static int Login(SOCKET sock);
-static int GetLine(SOCKET sock, char *prompt, Tcl_DString *dsPtr);
+static int GetLine(SOCKET sock, char *prompt, Tcl_DString *dsPtr, int echo);
 static char *server;
 static Tcl_HashTable users;
 static char *addr;
@@ -295,7 +295,7 @@ EvalThread(void *arg)
 retry:
  sprintf(buf, "nscp %d> ", ncmd);
  while (1) {
- if (!GetLine(aPtr->sock, buf, &ds)) {
+ if (!GetLine(aPtr->sock, buf, &ds, 1)) {
  goto done;
  }
  if (Tcl_CommandComplete(ds.string)) {
@@ -348,29 +348,94 @@ EvalThread(void *arg)
  */
 
 static int
-GetLine(SOCKET sock, char *prompt, Tcl_DString *dsPtr)
+GetLine(SOCKET sock, char *prompt, Tcl_DString *dsPtr, int echo)
 {
- char buf[1024];
+
+#define TN_IAC 255
+#define TN_WILL 251
+#define TN_WONT 252
+#define TN_DO 253
+#define TN_DONT 254
+
+#define TN_ECHO 1
+
+#define TN_EOF 236
+#define TN_IP 244
+
+ char do_echo[] = {TN_IAC, TN_DO, TN_ECHO};
+ char dont_echo[] = {TN_IAC, TN_DONT, TN_ECHO};
+ char will_echo[] = {TN_IAC, TN_WILL, TN_ECHO};
+ char wont_echo[] = {TN_IAC, TN_WONT, TN_ECHO};
+
+ unsigned char buf[2048];
  int n;
+ int result = 0;
+
+ /*
+ * Suppress output on things like password prompts.
+ */
+ if (!echo) {
+ send(sock, will_echo, 3, 0);
+ send(sock, dont_echo, 3, 0);
+ recv(sock, buf, sizeof(buf), 0); /* flush client ack thingies */
+ }
 
  n = strlen(prompt);
  if (send(sock, prompt, n, 0) != n) {
- return 0;
+ result = 0;
+ goto bail;
  }
+
  do {
  if ((n = recv(sock, buf, sizeof(buf), 0)) <= 0) {
- return 0;
+ result = 0;
+ goto bail;
  }
  if (n > 1 && buf[n-1] == '\n' && buf[n-2] == '\r') {
  buf[n-2] = '\n';
  --n;
  }
+
+ /*
+ * This EOT checker cannot happen in the context of telnet.
+ */
  if (n == 1 && buf[0] == 4) {
- return 0; /* Received single EOT (i.e., ^D). */
+ result = 0;
+ goto bail;
  }
+
+ /*
+ * Deal with telnet IAC commands in some sane way.
+ */
+ if (n > 1 && buf[0] == TN_IAC) {
+ if ( buf[1] == TN_EOF) {
+ result = 0;
+ goto bail;
+ } else if ( buf[1] == TN_IP) {
+ result = 0;
+ goto bail;
+ } else {
+ Ns_Log(Warning, "nscp: "
+ "unsupported telnet code received from client");
+ result = 0;
+ goto bail;
+ }
+ }
+
  Tcl_DStringAppend(dsPtr, buf, n);
+ result = 1;
+
  } while (buf[n-1] != '\n');
- return 1;
+
+ bail:
+
+ if (!echo) {
+ send(sock, wont_echo, 3, 0);
+ send(sock, do_echo, 3, 0);
+ recv(sock, buf, sizeof(buf), 0); /* flush client ack thingies */
+ }
+
+ return result;
 }
 
 
@@ -402,8 +467,8 @@ Login(SOCKET sock)
  ok = 0;
  Tcl_DStringInit(&uds);
  Tcl_DStringInit(&pds);
- if (GetLine(sock, "login: ", &uds) &&
- GetLine(sock, "password: ", &pds)) {
+ if (GetLine(sock, "login: ", &uds, 1) &&
+ GetLine(sock, "password: ", &pds, 0)) {
  user = Ns_StrTrim(uds.string);
  pass = Ns_StrTrim(pds.string);
  hPtr = Tcl_FindHashEntry(&users, user);
@@ -423,10 +488,10 @@ Login(SOCKET sock)
  }
  if (ok) {
  Ns_Log(Notice, "nscp: logged in: %s", user);
- msg = "Welcome to AOLserver\n";
+ msg = "\nWelcome to AOLserver\n";
  } else {
  Ns_Log(Warning, "nscp: login failed: %s", user ? user : "?");
- msg = "Access denied\n";
+ msg = "\nAccess denied\n";
  }
  (void) send(sock, msg, strlen(msg), 0);
  Tcl_DStringFree(&uds);
@@ -464,6 +529,6 @@ ExitCmd(ClientData arg, Tcl_Interp *interp, int argc, char **argv)
 
  stopPtr = (int *) arg;
  *stopPtr = 1;
- Tcl_SetResult(interp, "Goodbye.", TCL_STATIC);
+ Tcl_SetResult(interp, "\nGoodbye\n", TCL_STATIC);
  return TCL_OK;
 }